This invention relates to an electrical resistance wall heater, and more particularly to a wall heater which is primarily intended to be permanently mounted within the wall of a building by fixedly mounting a wall box to a structural wall member (e.g., a stud), with the wall box extending out through an opening in the wall sheathing. A combination blower/heater assembly is mounted within the wall box so as to draw room air into the wall box, pass it over the heater, and forcibly discharge the heated air into the room.
Generally, portable, fan forced heaters typically forcibly draw cool, room air in through the back of the heater passed it over an electrical resistance heating element, and force the air out the front of the heater, with the air traveling substantially in axial direction through the heater. This axial flow of air through the heater ensured that cool room air was freely drawn into the heater and uniformly passed over the heating elements thereby to ensure that the heating element works at a desired operating temperature such that the tips or other portions of the heating elements would not be heated to visible incandescent temperatures at which they would glow red.
However, in built-in wall heaters which are enclosed within the wall of a building, the inlet air is typically drawn into the heating element via an inlet opening, passed over the heating elements, and then discharged from an outlet opening separate and apart from the inlet opening. However, the incoming air oftentimes drew some of the discharged heated air back into the heater. This increased inlet air temperature and caused some or all of the open heater coil elements to operate above their desired temperature level (i.e., to glow red). The fact that some or all of the heating elements might glow red was undesirable because this shortened the operating life of the heating element, caused concern on the part of consumers utilizing the heater, and resulted in less operating efficiency for the heater.
Further, in many prior art wall heaters, the heating element and fan unit were difficult to electrically connect within the roughed-in wall box mounted within the wall. Typically, with prior art wall heaters, the wall box mount was mounted within the wall and a portion of the wall box was in register with an opening in the wall sheathing. A power wiring within the wall extended through a knock-out opening in the wall box. In these prior art wall heaters, it was necessary for the installer to physically position the heater/blower assembly proximate the wall box. While holding the relatively heavy heater/blower assembly in close proximity, but not fully installed in the wall box, manually making the electrical connections between the heater wiring harness and the electrical supply line. Only after the electrical connections were fully made could the heater/blower assembly be secured in position within the wall box. This oftentimes increased the labor and costs involved with installing such wall heaters. Additionally, this task was oftentimes difficult to do because the heater wiring harness would be of relatively short length, thus requiring the installers to make the wiring connections with little or no access to the wiring ends where the wiring connections were to be made.
Also, with prior art wall heaters having separate inlet and outlet openings, the openings were relatively small (as compared to the size of the wall box) and they were spaced apart so as to prevent entrainment of the discharged heated air with the incoming room air. Thus, the overall size of these prior art wall heaters tended to be somewhat undesirably large so as to accommodate the separate inlet and outlet openings, and so as to ensure that there was adequate separation between the inlet and outlet openings thereby to effectively prevent the heated air discharge from the outlet opening becoming entrained with the room air being drawn into the heater.